Process for sizing fibrous material



Nov. 28, 1933. P. w. CODWISE 3 I PROCESS FOR SIZING FIBROUS MATER IAI- v Filed Nov. '8, 1927 gwumm'a 4 4/41: C'bp W16:

" UNITED STA Patented Nov. 28, 1933 1.93731? I PROCESS FOR, SIZING FIBROUS MATERIAEJ Philip W. Codwise, Kenmore, N. "lZ assigner,

by mesne assignments, to Certain-teed Products Corporation, a corporation ct ltl'aryland Application November 55,

4 Claims. (oi. os-eoi This invention relates to sizing of fibrous material and has particular reference to an improved process of sizing and to an apparatus for carrying out said process.

5 The invention consists in the features, combinations and arrangements, hereinafter de scribed or claimed, for carrying out the above stated objects and such other objects as will hereinafter appear.

Ill The invention may be understood readily by reference to one illustrative embodiment thereof described in the following specification, such embodiment comprising apparatus usually emplayed in the manufacture of paper. lnaccordance with the invention, the paperis run through the usual battery of drying rolls, calendered, and then sized. The sizing is applied after the fibrous sheet has been at least partially hardened or compressed so that the sizing will 29 belocalized on and at the surface of the sheet and prevented from penetrating to any substantial depth therein. Paper prepared in accordance with this invention possesses a. better sized surface and one that is superior in hardness,

smoothness and glossiness. With such characteristics, it is especially adapted as cover sheets to improve the appearance of wallboarcls; and render them less liable to injury when drawn one over the other in the course of handling.

so The accompanying drawing is a side elevation of the dry end of a paper apparatus, together with means on the calender tor applying the sizing.

'Figure l. is a fragmentary view of the dry 85 end of the papermaking machine showing the -46 In accordance with the present invention, the

paper may be formed in apparatus usually employed in the manufacture of paper. The paper is run through the usual drying rolls 2: which are located at the dry end of the apparatus and then through one or more calender stacks 3 and 4. Ordinarily'only one calender stacl: is necessary to properly finish the paper but two or more stacks may be conveniently employed to give a better finish. v 1 50 Means 5 is associated with the calender stack,

or any one stack if several are used for applying the sizing to either or both surfaces of the sheet. Preferably, the sizing is applied to the upper surface of the sheet, and the applying means comprises a trough 6 for holding a quantity of sizing which is fed from a reservoir '7 through feed line Si in which a valve means 9 is inserted to regulate the flow. Trough 6 is reduced in thickness and contoured on one edge to conform to the face of the calender rolls with which it cooperates for distributing thereon a thin film of sizing. The trough can be conveniently attached to the calender supporting standards and then adjusted to receive and, spread a uniform depth of sizing over the roll coextensive with the width of the paper to be sized. Altho the flow of sizing from the reservoir may be regulated to avoid any accumulation other than that necessary to provide the Y film, an overflow outlet iii may advantageously N be employed to further insure regularity of the supply in the trough. The feed from the reservoir is regulated so that there will be a continuous slight overflow through the outlet. This overflow is collected in a receptacle l1 and returned to the reservoir.

The paper is warm after passing over the drying rolls and in this condition is readily adapted to receive the sizing uniformly over its surface but the heat has a tendency to draw the sizing from 30 the surface into its inner structure, thereby impairing the finish and at the same time requiring a greater supply oi sizing material. Inasmuch as paper used in wallboard manufacture is relatively thick and course in texture, an extraordinary supply of sizing would be required to properly finish the surface unless the paper was constructed to resist or impede absorption. Moreover the nature of the sizing itself is preferably of such a nature to resist being absorbed after the paper is cooled.

The sizing comprises a 1 B solution of a starch product in water and is preferably of a concentration between the limitsof l and 3 /2 Feculose, an acetated starch; is one example of a siutablestarch product and is suited to run at a temperature of F. Altho 1 Be is a suitable strength, this may be altered to meet varying conditions. Ordinary starch or a thin boiling starch such as alkali treated starch may be used if desired. Before applying the sizing, the sheet is compressed and hardened by being run through at least a part of the calender apparatus. The paper in being hardened and compressed before application of the sizing does not absorb the sizing to any great extent, and hence the sizing is localized substantially upon and completely over the surface of the paper. This action is further assisted by running the sized sheet over additional. calender-ins rolls, whereby it is cooled and ren- 11 out its entire mass. Therefore, practically the entire sizing solution is utilized to improve the exterior surface of the paper.

Obviously the invention is not limited to the details of the illustrative apparatus'and method of manufacture, all or any of which may be variously modified. Moreover, it is not indispensable that all features of the invention be used conjointly as certain features may be em-- sheet that the sizing applied is for the most part a surface coating. 1

dered less susceptible to absorbing sizing through- 2. In a continuous process for making and surfacing paper the step of applying sizing of low penetrating power to the paper surface but only after the paper has been first subjected to drying and then to pressure sufficient to so compact the sheet that the sizing applied is for the most part a surface coating, the sizing being applied to the paper,. after the first compression, under a second compression between calender rolls.

3. In a continuous processfor making and surfacing paper the step of applying sizing of low penetrating power to the paper surface but only after the paper has been first subjected to drying and then to a pressure sufficient to so compact the sheet that the sizing applied is for the most part a surface coating, and the further step of again applying pressure to the coated sheet after the application of the sizing.

4. The process according to claim 1 in which the sizing used is a water solution of starch material.

PHILIP W. CODWISE. 

